Synchronizing device for transmissions



Dec. 9, 1952 K. s. E. WICKBERG 2,620,907

svucmzomzmc DEVICE FOR TRANSMISSIONS 4 SheB'LF-Shaet 1 Filed Oct. 10. 1949 Fl G INVENTOR Karl Gustaf Eugen Wickberq,

ATTOR N E YS Dec. 9, 1952 K. G. E. WICKBE Z'RG 0 I SYNCHRONIZING DEVICE FOR TRANSMISSIONS Filed Oct. 10, 1949 4Sheets-Sheet 2 FIG. 2

INVENTOR Karl Gustaf Eugen Wickberg,

ATTORNEYS Dec. 9, 1952 K. e. E. WICKBERG SYNCHRONIZING'DEVICE FOR TRANSMISSIONS 45heets-Shet 4 Filed 001;. 10, 1949 INVENTOR Karl Gustaf Eugen Wickberq,

ATTORNEYS Patented Dec. 9, 1952 SYNCHRONIZING DEVICE FOR TRANSMISSIONS Karl Gustaf Eugen Wickberg, Stocksund, Sweden Application October 10, 1949, Serial No. 120,441 In Sweden October 11, 1948 8 Claims.

The present invention relates to synchromesh transmissions and particularly to a synchronizing device for engaging various gears in constant mesh gear transmissions, especially in connection with motor vehicles, and irrespective of whether, at the beginning of the shifting operation, the engine driven input shaft and its associated gears in the transmission case rotate at a lower or higher speed than the output or main shaft, at the intended point of engagement between the two shafts, the synchronization being obtained by varying the speed of the engine.

In synchronizing devices of hitherto known types synchromesh gear changing has been accomplished by braking or accelerating the rotary masses in the transmission case against the output or main shaft by means of any one of a plurality of friction devices until a speed will have been imparted thereto which corresponded to the speed of the output shaft. Such a device, however, particularly in its application to heavy vehicles involving necessarily comparatively large diameters, suifers from considerable disadvantages such as a relatively rapid wear down of the friction devices, which is one of the reasons why this known device has only been advantageously employed in low-weight vehicles such as passener cars and the like.

Therefore, in the case of heavier vehicles, one has been confined, in changing down, at least, to the oldest way of accomplishing synchromesh which consists in double declutching in conjunction with foot accelerating the engine. This is carried out in the following manner: After declutching and placing the gearshift lever in neutral, the clutch pedal is released and the engine accelerated for which operation the vehicle operator is obliged to use his right foot. The clutch pedal is again depressed (declutching) when the operator estimates the rotating gears to be synchronized and thus capable of being connected with each other in synchromesh by moving the gearshift lever.

The attainment of an exactly defined synchromesh by this method, however, is entirely dependent on the operators personal skill, and moreover the shifting is rather time-consuming and makes it impossible for the operator to operate the foot brake of the vehicle when a gear shifting operation is being performed. As a result of lacking synchromesh the operator most commonly has to change his gear forcibly which results in gear-clashing. When changing into a higher speed no serious difliculties have been experienced even in heavy vehicles, nor has any undue wear been involved, in that recent methods of shaping the gear teeth will have eliminated most of the problems in connection with gearchanging operations in this direction.

The present invention has for its objects toprovide a synchronizing device which is reliable and sure of operation for both heavy and lightweight vehicles, and to avoid the necessity of operating the accelerator pedal in conjunction with double declutching, in that the accelerating means of the vehicle is arranged to be automatically actuated, in such instance, through the in-' termediary of any suitable other member partaking in the gear changing operation, and, as the case may be, to avoid the double declutching by causing the occasional operation of the engine clutch to be carried out automatically.

For the objects stated, according to the in vention, a synchronizing device of the kind described is mainly characterized in combination by dog clutch means arranged between the re-' spective speed gears of the transmission and being such as only to be capable of being engagedwhen both its clutch members rotate at the same speed, the engagement of said clutch members being prevented by a thrust member at least when the speed of the clutch member associated with the output shaft of the transmission isgreater than the speed of the other clutch member, the angular position of said thrust member relative to one of said clutch members being dependent on the sense of rotation of the input shaft of the transmission relative to the output shaft thereof, auxiliary actuating means for the accelerating means of the engine cooperating with the gear shifting mechanism and/or engine clutching means upon changing down, and retaining or stop means cooperating with said actuating means, in such a manner that, after the engine clutch, following disengagement thereof in conjunction with placing the gearshift-lever in neutral, has been again occasionally engaged, either by releasing the clutch pedal or by an auxiliary clutch automatically engaged in the declutching position of said pedal, the engine is accelerated Said thrust member, being suitably a disc, ring or sleeve, which is angularly displaceable between two limits and is formed with a number of radial projections or teeth peripherally cooperating with shoulders or teeth formed on one of the dog clutch members in order to prevent or permit, respectively, the engagement of the dog clutch, need not be a new part of the transmission, since a well-known thrust washer or spacer already present at the respective gear on the output shaft might be formed in such a manner that it may be adapted to serve simultaneously as'said axial thrust member.

Since changing from a lower into a higher gear usually will not involve any material difficulties, as the speed difference at the point of engagement will rapidly decrease, the said thrust member is preferably arranged upon changing into a higher speed to occupy a position such that the interengagement of the dog clutch members will not be prevented thereby, in which case the clutch members are, or may be, provided with any suitable retarding means in order to facilitate the synchronization of the dog clutch member rotating with the input shaft and the masses rotating therewith with the other dog clutch member.

Two embodiments of the synchronizer according to the invention will now be described by way of example, reference being had to the accompanying drawings. It should be pointed out, however, that the invention is by no means restricted to exactly these embodiments which are to be considered as being merely illustrative, since the equivalent operation is obtainable in many different ways without departing from the inventive conception.

In the drawings:

Fig. 1 is a side elevation, partly in section, of a constant-mesh transmission and a conventional engine clutch, in combination with a synchronizing device according to one embodiment of the invention.

Fig. 2 is a vertical section and elevation taken along the lines II-II in Fig. 1.

Fig. 3 is a side elevation, partly broken away and partly exploded, of a portion of the transmission, several parts being omitted in order to illustrate the mutual arrangement of other parts.

Fig. 4 is a section along lines IVIV in Fig. 3.

Fig. 5 is a diagrammatic side elevation of another embodiment of the synchronizing device having a modified arrangement for actuating the engine accelerating means upon changing down, and also a special auxiliary clutch for the occasional engagement of the main clutch before actuating the accelerator.

Referring now to the embodiment illustrated in Figs. 1 and 2, numeral 42 designates the engine crankshaft which carries one member, viz. the flywheel, of a well-known friction main clutch or engine clutch II which belongs to the clutching mechanism 9 comprising also the clutch pedal 13, throwout fork 28, throwout bearing 29, and, within the clutch cover H, the clutch springs and a clutch disc which is axially movable and non-rotatably mounted on the input shaft 1 of the transmission 4, and which is adapted to be pressed against the rear face of said flywheel by said clutch springs, and to be released therefrom by the clutch pedal I3 being depressed by the vehicle operator causing the throwout fork to displace the throwout bearing axially against the action of said clutch springs. In the clutching mechanism 9 there is always a certain amount of lost motion causing a play 21 normally to be present between the throwout fork 28 and throwout bearing 29. This play, according to this invention, may be utilized in a manner and for a purpose to be described further below.

The transmission 4 is of the substantially wellknown type comprising dog clutches I arranged between the various speed gears and one member 2 of which is formed integral with the respective gear wheels, such as H, freely rotatable on the main or output shaft 5, and the other member 3 of which is, by means of the gearshift-lever l2 and a gearshift-fork 43, axially displaceable along splines or the like on said output shaft 5 into and out of engagement with the corresponding dog clutch member 2 in order to connect the output shaft 5 to or disconnect the same from the input shaft 1, either directly or via the corresponding counter gears 44, 45, 45 on the countershaft 41. The construction of the dog clutch is clearly shown in Figs. 3 and 4. For the sake of simplicity the two dog clutch members 2 and 3 are shown as having only few teeth or dogs, which for member 2 are illustrated at 48 and for member 3 at 49, the corresponding recesses in the two members being shown at 50. Between the two members 2 and 3 there is inserted a thrust member in the form of a sleeve, disc or ring 6 which is mounted on the main shaft in such a manner as to be freely rotatable thereon and to be nested with member 3, said thrust member being, preferably resiliently by compression coil spring 5i, gently urged against the adjacent face of member 2, the faces of said thrust member 5 being formed for transmitting axial thrust in order to obtain a minimum of frictional work which should be slightly greater on the input face of said thrust member 6. Thus the thrust member or ring 5 is not intended to transmit any braking or accelerating torque but simply to be rotated with and by the clutch member 2 into certain limits or intermediate positions relative to the clutch member 3. The thrust member or ring 6 is provided with a number of projections 53 angularly movable within limited recesses 52 in the output shaft 5, which projections when said ring 6 is in a certain limit position permit the dog clutch member 3 to be moved into engagement with the clutch member 2 when the clutch members rotate at the same speed, whereas at least when the speed of the clutch member 3 mounted on the output shaft 5 of the transmission is greater than the speed of the other clutch member 2, i. e. in changing down, the engagement of the dog clutch members 2, 3 is prevented by said ring 6 in that the latter has then been rotated into such a limit position that its projections 53 are aligned with clutch teeth 49 on member 3.

When the gear rotating with the input shaft 1, e. g. H, and its dog clutch member 2 rotate at a greater speed than the clutch member 3 rotating with the output shaft 5, which is normally the case when changing into a higher speed, the gear I! and its associated masses are to be retarded in order to obtain synchronism. This may be efiected in various ways, for instance by connecting the gear 11, through shaft 1 and, as the case may be, through two countergears 45, 44, to the engine crankshaft 42 via the main clutch II which is operated by the clutch pedal l3 or by a special auxiliary clutch (14, Fig. 5), and thus retarding the same together with the engine, or in any suitable othermanner. In order to cause a certain amount of retardation to be obtained and thus facilitate a synchromesh engagement of dog clutch I in conjunction with declutching and shifting the gear, therefore, the clutch teeth 48, 49, or some of them, may for instance in a manner well-known to the art be peripherally chamfered on those surfaces I5 which will meet when the clutch members are moved toward and against each other, so that they will slip until exactly synchronous speeds are obtained at the point of engagement.

However, in changing from a higher into a lower speed, the gear I! and its associated clutch member 2 will have to be accelerated, since in this instance the output shaft 5 and hence the clutch member 3 will rotate at a greater speed than the input shaft I and the first-mentioned clutch member 2. This is effected by means of the engine in that, by means to be described further below, the fuel supply to the engine will be increased after the engine clutch II having been occasionally engaged. Such an increase of the fuel supply, for reasons hereinbefore discussed, should be controlled automatically, which is of particular importance if the operator has not been able to determine whether the engine should be retarded or accelerated, or how great the speed changes should be in order to enable the engagement of the new gear.

For this purpose, the arrangement according to Figs. 1 and 2 comprises supplementary or auxiliary actuating means I9 for the engine accelerating means, said actuating means I0 being arranged upon changing into a lower gear to cooperate with the gearshift mechanism 8 and engine clutch mechanism 9 in such a manner that, after the engine clutch I I havin been disengaged in conjunction with placing the gear-shift-lever I2 in neutral and then having again been occasionally engaged by releasing the clutch pedal, the engine will be accelerated through the action of moving the gear-shift-lever toward the new gear position, until equal speeds of the dog clutch members 2 and 3 will have been obtained, in which condition the thrust member or ring 6 will have been rotated into the limit, in which said dog clutch members may be engaged, i. e. the lower gear synchronously engaged. The ring or thrust member 5 acts as a reaction bearing member against the operating force applied to the gear shift lever I2. Upon synchronous speeds being attained this reaction bearing member will be disabled in its reactive function whereby the vehicle operator will obtain, at the proper instant, an indication to complete the gearshifting operation by pushing home the gearshift-lever, after the engine clutch has been disengaged, either by foot operating the same or automatically by means to be described further below.

In the embodiment shown in Figs. 1 and 2 the auxiliary actuating means II] for the engine accelerating means comprises movement transmitting means which include two parts, viz. a body I9 reciprocable in guides provided in the cover [8 of the transmission 4, and a latch or looking rod 20 reciprocable perpendicularly to the movement of said body I9. The body I9 forms a bearing and support for the gearshift lever I 2, and two oppositely acting compression coil springs 35, 36 urge the body I9 into a central or equilibrium position in which the upper end of said latch or looking rod 29, which end is formed as a cam-follower, engages into a corresponding cam-slot in the lower surface of said body I9.

The lower end of rod 20 is rounded and rests on a short lever 2| rigidly connected to a pivot 54 which is passed through the wall of the transmission case 4 projecting outside the same, the projecting portion thereof being provided with a relatively longer lever 22 the free end of which is connected to the engine accelerating means in any suitable manner, such as by a Wire or rod 23.

The auxiliary actuating means I 0 further comprise a linkage cooperating with the clutch mechanism 9 and gear-shifting mechanism, in the actual case with the lever 22 indirectly actuated by the gearshift-lever, said linkage consisting of a double-armed lever 25 and two link rods 24, 26 articulated thereto, and also of a lever 55 secured on the pivot of the throwout fork 28. In this linkage there is always a play which is formed mainly by the usual play or lost motion between the throwout fork 28 and the throwout bearing 29. The double-armed lever 25 is pivotally connected at point 33 to a lever 56 integral with the clutch pedal I3. One link rod 26 connects the lower end 3| of lever 25 with the free end of lever 55 on the pivot of the throwout fork 28. The other link rod 24 connects the upper end 32 of lever 25 with an attachment 33 which is secured on lever 22 at a suitable distance from its pivot 54, and through which attachment 33 the end of said link rod 24 freely passes and is provided with a stop nut or the like which rests against the attachment 33 when the body I9 is in its neutral position and the clutch pedal I3 is in its unoperated position (engine clutch engaged).

Upon changing from a higher into a lower gear the arrangement hereinbefore described will operate in the following manner: When the clutch pedal I3 is depressed in conjunction with placing the gearshift-lever I2 in neutral, the operating force is transmitted from the clutch pedal I3 through lever 56, lever 39-3I, rod 26, and lever 55 to the throwout fork 28, whereby the play 21 is eliminated and the clutch I l is disengaged, whereupon the link rod 24 is pulled so that it will tend to rock the lever 22 and thus lever 2! which action, however, is prevented by the latch or locking rod 29 the upper end of which is pressed into the cam-slot 3? in the body I9. The attachment 33 thus acts as a fixed reaction thrust member for the power energized link and lever system. Thereafter the clutch pedal I3 is released for effecting the occasional engagement of clutch ll. Thereupon the link and lever system will be deenergized so that the throwout fork 28 will return into its position of rest whereby the play 2! is again introduced into the linkage It. As thereafter the gearshift-lever I2 is moved toward the new gear position the body I9 will depress the latch or looking bar 29 in that cam-slot 31 will be pressed against the cam-follower surface of said rod, whereupon the body I9 can be moved in one direction or the other so that the body I9 together with said springs 35 and 35 will act as an energy storing device. Thus when the rod 20 is depressed it will :act on the lever 2I so that pivot 54 is rotated causing lever 22 to be rocked and the accelerating means of the engine to be actuated through string or rod 23. This increases the speed of the engine and thus that of the input shaft 1 and of the dog clutch member 2 rotating therewith, until said speed will be equalized with the speed of the output shaft 5 and thus with the speed of the dog clutch member 3. When lever I2 is pivoted about its ball and socket support in unit I8, the resistance of the slidable shift yokes 43 due to theblockingaction ofelement i results in the lever l2 beingpivotally moved about its connection 8 with the shift-yokes 43,' thus-causing the yieldablepivot'support members I9 to slide inun'it IB againsttheactionof 'springs 35 or 3 5 with a consequent storing of energy which is sufficient tocomplete the gear shifting operation when elements 6 are-correctly positioned for clutch engagement. The" operator 'will now be enabled to move his-*gearshift-lever into t'he new gea'r'position during which'the operator; of course, as usual will "declutch by: depressing the clutch pedal I 3 causing the linkage to be energizedagain' and the body I 9"'to' be forced back into neutral.

The modified arrangement :shown 1 in Eig. 5 differs from the-preceding embodiment mainly in that; instead of through double 'dec'lutching, the occasional engagement'of the engineclutch H in conjunction with changing from a'hlgher into -a lower gea r is carried out "by auxiliary means ld for operating the'main clutch II normally I operated by means of the engine I clutch pedal t3,'an'd that, during the occasional engagement of theengine clutch, the engine accelerating means is'actuated by the clutch pedal I3 instead of by the gearshift-lever I2.

I The "clutch members of the auxiliary means It for operating the mainclutch II are constituted by the clutch members of the engine main clutch I I proper, i. e. by the engine flywheel and a clutch "disc :cooperating therewith, whilstthe actuating means for said 'auxiliary'means M-is formed by a hydraulic cylinder and piston farrangement 38. The latter is operated by, for instance, a two-way valve 49 the actuating member 51 of whichv projects into the path of movement of a cam member 4|. arranged on the clutch pedal I3, and in such a position that the valve 40 will be shifted when,'after having been depressed into its declutching position, the clutch pedal I3 is depressed slightly further. Upon shifting the valve 40, the piston 58 is displaced in the cylinder 59, and a piston rod iii] connected to the piston operates one end of a double armed lever El the opposite end of which is pivoted "on a fixed support or bracket 62. A'reciprocably guided push and"pull'rod 34 ispivotally connected to lever SI at a relatively short distance from the support 62 and .passeshorizontally through a fixed plate or the like 84, the free end of said rod being provided with collar 33. Betweenthe collar-"33 and the'fixed plate 64' there is inserted a compression coil-spring 63 around rod 34.

In a manner similar to that of the preceding embodiment, a link and lever system is provided comprising a double-armed lever 25 which is pivoted in a point 30 to a lever'56 integral with the clutch pedal l3. The lower end- 3| of lever 25 is, as before, connected through a link rod- 25 to a lever 55 secured on the pivot of the throwout fork 28. The upper end'32 of lever 25 is also, as before, arranged to cooperate through a link Hwith a reaction bearing member'which is'movable, and which in this instance is formed by the collar 33 on the spring biased push and pull rod 34.

An actuating member in the form of a spring biased push rod 39 is connected to the engine accelerating means and is arranged in such a position, for instance in the-toe board of the vehicle, that it may be operated by the clutch pedal after the latter has been depressed beyond the position in which the valve '40 has been shifted.

'The operation of the arrangementdescribed is asfollows When changing from a lower into 'a higher speed gear the gearshifting operation runs in the normalway, i. e. the clutch pedal I3 is-depressed, butnot -to a sufficient extent to cause shifting ofvalvedfl. Upon so doing the operating force is transmitted through lever 56, 1ever-30-3I, link rod 2 6' andlever 55"to the throwout fork 28 w-hich-actuates the throwout bearing 29 so that the engineclutch' II is disengaged. The operating force is, of course, transmitted also through lever 3El32-and link rod 24 50 that the latter ispressed against the collar :33 but isnot capable of overcoming the tension of the 1spring63. During this operation the gearshift-lever- I2 is first placed in neutral Sand is then'moved' into the new gear: position, after the input shaft-I of the transmission and the masses associated therewith having been" retarded to a speed equal to thatof theoutput shaft 5, due to'theiresistance present in the mechanisms and the retarding meansi of' the dog clutch I, and; as thecase may 'be," inrconjunction with engagement of' the auxiliaryiclutch' I4.

'When changing from a higher intc a lower speedgearclutch pedal i3 is depressed into-its disengagement :position, and in conjunction therewith gearshift-lever I2 is placed in neutral. Thereafter the clutch pedal 'is'further' depressed so that'its cam membei" 4I willshift the actuat-mgmemberii'i of the two-wayvalve 40. Upon doing this pressure fluid will be supplied to the hydraulic cylinderfill and move the. piston 58 in such a-direction that the latter will 'move lts piston rod 60 to the 'leftin Fig. 5. This 'willrock the leverSI in'such adirection that the push'an'd pull rod 34 will-be pulled to' the left according to the figureagainstthe action of spring 153. The collar 33 which has up till now acted as a reaction member or stop-against the operating force exerted on the clutch pedal, thus will be pushed to the left. This releases the tension'of the clutch springs inengine clutch I I through the link rods 24 and 26 andlever 25, so that the throwout bearing 29 will be moved to the right as seen in the figure and the engine clutch will be engaged. Then the clutch pedal I3 is further depressed while the engine clutch ii isthus-engaged. This actuates the engine accelerating means 39 causing the-engine and thus the dog clutch member 2 at the point of engagement in the transmission 4 to'be aecelerated until synchronous speeds of the same and the other dog clutch member 3-are obtained, the ring or thrust member -6 having then been rotated into such a limit that the dog clutch'can be engaged by moving the gear-shift lever into the new speed gear position, in conjunctionwith-which operation the clutch pedal I3 is released, whereby the samewill first cease to actuate the accelerating means 39 and then shift back thevalve 40' so that the pressure supply to the piston 58 is interrupted and the spring 63 willbe able-to return the push and pull rod 34 with its collar or reaction member 33 into their normal position.

It will-be understood that the invention can be modified in various respects without departing from its spirit. Thus, for example, servo mechanism may be arranged-so as to actuatethe linkage or the clutch'pedal occasionally after the transmission being placed in neutral in order to the prevailing condition of speed relation between accelerate the clutching operation, or to indicate the shafts. -With'- the embodiments described it will be possible under all conditions to sh ft gea s when the engine is running. Sometimes it may be required, however, to be able to start the engine by letting the vehicle roll down a hill or otherwise, with the direct gear engaged, if, for instance, the starter is inoperative. In such a case the thrust member 6 cooperating with this gear will have to be slightly modified or to be associated with some simple accessory of a nature such that said thrust member will not under such circumstances prevent the engagement of the direct gear. The above-mentioned and other modifications of the invention, however, are of a nature to be readily obvious to anyone skilled in the art.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, what I claim is:

1. A synchronizing device for engaging various gears in constant-mesh gear transmissions in motor vehicles having an input shaft, an output shaft and speed gears associated therewith irrespective of whether, at the beginning of the shifting operation, the engine driven input shaft and its associated gears in the transmission case rotate at a lower or higher speed than the output or main shaft, at the intended point of engagement between the two shafts, comprising dog clutch members forming dog clutch means arranged between the respective speed gears of the transmission and capable of engagement only when the clutch members thereof rotate at the same speed, a thrust member preventing engagement of said clutch members when the speed of the clutch member associated with the output shaft of the transmission is greater than the speed of the other clutch member, the angular position of said thrust member relative to one of said clutch members being dependent on the sense of rotation of the input shaft of the transmission relative to the output shaft thereof, gear shifting means comprising a movably supported gearshift lever adapted when operated to cause displacement of one of said dog clutch members to engage or disengage the dog clutch means, engine clutch means operable to engaged condition and disengaged condition to connect and disconnect the engine of said vehicle to and from said input shaft, respectively, accelerating means for said engine, main actuating means for said accelerating means, auxiliary actuating means for said accelerating means of said engine operably connected between said gear shifting means and said engine clutch means and adapted, when said engine clutch is engaged, to actuate said accelerating means in a throttle opening direction upon operation of said gearshift lever, and when said engine clutch is disengaged in a throttle closing direction, whereby, when said engine clutch is engaged and said gearshift lever is operated to engage said dog clutch members in I,

said transmission with said thrust member in its blocking position, said engine is accelerated by said auxiliary means actuating said accelerating means until synchronous speeds are obtained at said point of engagement in said transmission, after which said auxiliary actuating means in a throttle closing direction through disengagement of said engine clutch in conjunction with termination of said gear shifting operation.

2. A synchronizing device as claimed in claim 1, in which said thrust member, upon changing from a lower into a higher gear, occupies a position allowing engagement of said dog clutch members, damping means for said dog clutch members for retarding the dog clutch member rotating with said input shaft and the masses associated therewith into a speed which is equal to that of the other dog clutch member.

3. A synchronizing device as claimed in claim 2 in which said thrust member comprises a thrustwasher for the respective speed-gears on said output shaft, said washer being shaped and. adapted to serve as the said thrust member.

4. A synchronizing device as claimed in claim- I, said auxiliary actuating means for said engine accelerating means being adapted, when said engine clutch is engaged, to actuate said engine accelerating means by the action of said gearshift lever being manually operated and comprising two-part movement transmitting means normally biassed for immovable connection with each other, and an operating member for said engine accelerating means operably connected to said transmitting means and said engine accelerating means in such a manner that said movement of said gearshift lever is transmitted to said accelerating means to render the latter active.

5. A synchronizing device as claimed in claim 1, said auxiliary actuating means for said engine accelerating means being adapted, when said engine clutch is disengaged, to render inactive said actuation of said accelerating means and comprising a linkage connected to said engine clutch means and said gear shifting means, said linkage being operable in response to the disengaging movement of said engine clutch means to block said movable support for said gearshift lever, play being normally present in said linkage when said engine clutch is engaged, said play being eliminated by movement of said auxiliary means for actuating said engine accelerating means through operation of said gearshift lever, or by renewed engine clutch disengagement movement, said movement being transmitted to said engine accelerating means whereby, upon changing down gears, said engine will be accelerated until synchronous speeds are attained at the intended point of engagement in said transmission.

6. A synchronizing device as claimed in claim 5, said engine clutch means comprising a clutch pedal for operating said engine clutch means, said auxiliary means for actuating said engine accelerating means comprising a linkage connected to said engine clutch means and said gearshifting means so as to enable disengagement of said engine clutch means upon operation of said gearshift lever, said engine clutch means comprising a throwout fork and a throwout bearing, said throwout bearing being adapted for axially transmitting the clutch pedal pressure against the action of the clutch engagement pressure, and vice versa, upon operation and release, respectively, of said clutch pedal, said play being normally present between said throwout fork and said throwout bearing when said clutch is engaged and being completely eliminated when said clutch is disengaged.

7. A synchronizing device as claimed in claim 6, said linkage comprising a double-armed lever pivoted at a point intermediate its ends to said engine clutch operating pedal, a rod adapted to transmit the movement of said clutch operating pedal to said throwout fork, said lever being at one end pivotally connected to said rod, a second rod pivotally connected to the other end of said lever, and a movable reaction support formed by a movable member associated with said gear shifting. means operable by said lever through said second rod;

8. A synchronizinggdevice.as claimed in claim 7; said movable reaction; support. comprising energystoring means,operable by said gear shift-. ing means; and situated in said gear shifting mechanism between the movable dog clutch member-and saidgear shifting means, retaining means lockingsaid 'energystoring means ina position of equilibrium when said, en ine clutchmeans is disengaged; said retaining :means being adapted, when said engine clutch is engaged and the engagement-of said dog clutch is prevented by said thrust-=member; to' release said energy storing meanswhereby; through the action of moving saidigear shifting meansforadesired gear position; said-energy-storingmeans is, displaced-While storing energy-through said gear shifting means to an extent correspondingto-said play; to therebycause actuation of'said engine accelerating means until synchronous speeds are attained at said point-of engagement in said transmission, wherebyupon' disengagement of said engine 12 clutch .in .conj1 1nction with terminatingjhefifiar shifting; operation said; movable supnortswill, in dependence of the inactivating functionof; said auxiliary actuatingmeans and said energy storing means, he returned into its immovable ,position.

KARL GUSTAF; EUGEN WICKBERGL.

REFERENCE-S" CITED The .fo11owing.rreferencescare, of record: in the file. of, this patent:

UNIFIED -STATES2PA'IENTS 1 Number Name Date;v

1,665,825 Stevenss Apr; 10,1928 1,693,645 Fahrney" Dec; 4, 1928" 1,895,722 idcLearn Jan. 31', 19.33 1,955,845" Bush; s Apr.-24; 1934 2,102,755 Sinclair Dec. 21; 1937' FOREIGN PATENTS Number Country Date 629,467" France NOV. 10, 1927 

